The invention relates to a gas bubble generator for example of the kind used in sludge treatment in a digestion tank or digester, though it will be understood that a gas bubble generator as described herein may be used in other applications.
It is often necessary to create turbulance in a liquid or liquid containing solid matter such as sludge, such liquid or sludge being hereinafter referred to collectively as `liquid medium`. One way of creating turbulence is to pass a steady stream of bubbles through the liquid medium. Such bubbles as they pass upwardly through the liquid medium promote mixing in the medium and also act to break up or disperse scum on the surface when they reach the surface and burst.
Bubble generators used in digesters are immersed in the liquid medium and systematically create a bubble by forcing a gas out of a tube by a hydrostatic effect as liquid medium passes through the generator forcing a trapped pocket of gas therethrough prior to expulsion as a bubble. As the liquid medium contains solid matter which is often fibrous, known as `rag`, the rag can and usually does become caught in the generator on tight bends thereof. This has the disadvantage of either reducing the efficiency of bubble formation or preventing it altogether, while the construction of the generator makes it virtually impossible to clean by purging or mechanically by rodding. It is accordingly an object of the invention to seek to mitigate these disadvantages.